| 自贡市西山公园地形对地震动的影响 |
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| 引用本文： | 王海云,谢礼立.自贡市西山公园地形对地震动的影响[J].地球物理学报,2010,53(7):1631-1638. |
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| 作者姓名： | 王海云 谢礼立 |
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| 作者单位： | 中国地震局工程力学研究所,哈尔滨 150080 |
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| 基金项目： | 国家自然科学基金面上项目，国家重点基础研究发展计划项目，国家自然科学基金重大研究计划重点项目，国家自然科学基金青年基金项目，中国地震局工程力学研究所基本科研业务费专项 |
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| 摘 要： | 不规则地形和土层对地震动的影响较大,建(构)筑物选址及其抗震设防必须考虑地形和土层场地的放大效应,以避免或减轻其震害.利用自贡地形台阵记录的汶川地震(Ms8.0)的主震加速度时程,基于传统谱比法分别研究了地形和土层场地对地震动的放大效应.结果表明:(1)地形场地在低频的放大效应不明显,最大仅为1.24;在高频的放大效应较显著,在1~10 Hz频带,山顶的放大效应最大,EW、NS和UD地震动的最大放大效应分别为4.15、3.61和2.41,对应频率分别为5.72 Hz、6.46 Hz和7.44 Hz;在10~20 Hz频带,靠近山顶的山脊上某个地震动分量的放大效应最大,7#台站EW、5#台站NS和7#台站UD地震动的最大放大效应分别为9.10、5.56和2.52,对应频率分别为16.97 Hz、16.91 Hz和17.91 Hz.(2)地形场地的最大放大效应随高度有增加的趋势,且在0.1~10 Hz频带随高度增加的趋势更加明显.(3)土层场地水平向地震动在2 Hz以上开始明显放大,竖向地震动在4 Hz以上开始明显放大;EW、NS和UD地震动的最大放大效应分别为13.4、12.168和6.0,对应频率分别为6.94 Hz、7.55 Hz和10.8 Hz.(4)土层场地与地形场地的最大放大效应相比较,前者显著大于后者,对于水平向地震动,前者至少是后者的3倍以上;对于竖向地震动,前者至少是后者的2.5倍以上.(5)无论是地形场地还是土层场地,地震动的最大放大效应均有水平向大于竖向的特征.
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| 关 键 词： | 自贡地形台阵 汶川地震 地震动 地形效应 谱比法 |
| 收稿时间： | 2009-09-03 |
Effects of topography on ground motion in the Xishan park, Zigong city |
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| WANG Hai-Yun,XIE Li-Li.Effects of topography on ground motion in the Xishan park, Zigong city[J].Chinese Journal of Geophysics,2010,53(7):1631-1638. |
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| Authors: | WANG Hai-Yun XIE Li-Li |
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| Institution: | Institute of Engineering Mechanics, China Earthquake Administration,Harbin 150080,China |
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| Abstract: | Effects of both soil layer and irregular topography on ground motion are relatively serious, their amplification effects on ground motion must be considered in site selection and seismic fortification of buildings to prevent or mitigate seismic hazard of buildings. Utilizing acceleration time histories of the Wenchuan earthquake's mainshock recorded by Zigong topographic array located in Xishan park, Zigong city, the amplification effects of both soil and site topography on ground motions are analyzed and studied by traditional spectral ratio method. The results are as follows. (1) The amplification effect of topography at low frequency is not obvious, and the maximal amplification factor is 1.24. And the amplification effect of topography at high frequency is significant. In the frequency range from 1 Hz to 10 Hz, the amplification factor of hilltop is maximal, the maximal amplification factors of EW, NS and UD ground motions on hilltop are 4.15, 3.61 and 2.41 respectively, the corresponding frequencies are 5.72 Hz, 6.46 Hz and 7.44 Hz respectively. In the frequency range from 10 Hz to 20 Hz, the amplification factor of some components of ground motions on ridges in the vicinity of hilltop is maximal, the maximal amplification factors of EW (7#), NS (5#) and UD (7#) ground motions of ridges in the vicinity of hilltop are 9.10, 5.56 and 2.52 respectively, corresponding frequencies are 16.97 Hz, 16.91 Hz and 17.91 Hz respectively. (2) The maximal topographic amplification factors of ground motions tend to increase with elevation of the hill, and the trend in frequency range from 0.1 Hz to 10 Hz is more obvious. (3) The amplification effect of horizontal ground motion at soil sites is obvious when frequency is more than 2 Hz, and that of vertical ground motion is obvious when frequency is more than 4 Hz. The maximal amplification factors of EW, NS and UD ground motions of soil site are 13.4, 12.168 and 6.0 respectively, corresponding frequencies are 6.94 Hz, 7.55 Hz and 10.8 Hz respectively. (4) The maximal amplification factors of soil site are more than ones of topographic sites. For horizontal ground motions, the former is 3 times the latter at lowest. For vertical ground motions, the former is 2.5 times the latter at lowest. (5) For both topographic site and soil site, the maximal amplification factors of horizontal ground motions are more than the ones of vertical ground motions. |
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| Keywords: | Zigong topographic array Wenchuan earthquake Ground motion Topographic effect Spectral ratio method |
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